Rescuers pulled the men from the water, but spent hours looking for Ms Li. Ken Hoang died at a hospital while Ms Li is presumed dead in the river.

Phan Hoang was taken to St. Joseph Hopsital, where he is in stable condition.

"My friend said he heard a yell [for] help, you know. At first I didn't believe it, so we still kept walking this way to keep sightseeing. As we got closer, he heard it again and I heard it again, too. And as we got closer, we yelled out, 'Where you at?"' a witness told WLS.

"I kept saying who was he with? And they said he had a friend and girlfriend, too, that went under the water, but he couldn't find her. We called the police."

"Life's too short..I hope no one would ever have to go through something so unfortunate such as what has happened ... from the bottom of my heart I am sorry for what happened ... RIP Ken Hoang Lauren Li," he wrote.

Outpourings of grief and support for Li have appeared on friends' Facebook pages and Hoang's family has created a memorial fund page at Youcaring.com.

After less than a day, the fund had raised nearly $US5500 of a $US15,000 ($6085 to $16,600) goal to benefit the bereaved Hoang family.

"The lesson learned here is real simple," said Chicago Police Superintendent Garry McCarthy. "If your pets go onto ice, if you drop a cell phone or wallet, do not try and retrieve it."